Spiral wave chimera states in large populations of coupled chemical oscillators

The coexistence of coherent and incoherent dynamics in a population of identically coupled oscillators is known as a chimera state(1,2). Discovered in 2002(3), this counterintuitive dynamical behaviour has inspired extensive theoretical and experimental activity(4-15). The spiral wave chimera is a particularly remarkable chimera state, in which an ordered spiral wave rotates around a core consisting of asynchronous oscillators. Spiral wave chimeras were theoretically predicted in 2004(16) and numerically studied in a variety of systems(17-23). Here, we report their experimental verification using large populations of nonlocally coupled Belousov-Zhabotinsky chemical oscillators(10,18) in a two-dimensional array. We characterize previously unreported spatiotemporal dynamics, including erratic motion of the asynchronous spiral core, growth and splitting of the cores, as well as the transition from the chimera state to disordered behaviour. Spiral wave chimeras are likely to occur in other systems with long-range interactions, such as cortical tissues(24), cilia carpets(25), SQUID metamaterials(26) and arrays of optomechanical oscillators9.